Oil seal device for rotary piston internal combustion engine

ABSTRACT

In a rotary piston internal combustion engine comprising a center housing having a trochoidal inner peripheral surface, side housings provided at both sides of said center housing, a three apexed rotary piston is provided through an eccentric shaft within a casing formed by said center and side housings. An oil seal device is disposed in an annular groove formed on a thrust surface of the rotary piston including an oil seal ring having an annular recess or an annular step on the rear portion thereof. A U-shaped elastic seal ring is disposed in said annular recess or step and has two lips slidably and sealingly contacting at least one radially facing surface of said annular recess, said annular step or said annular groove, and a spring is disposed between said oil seal ring and said U-shaped elastic seal ring for pressing said oil seal ring and said U-shaped elastic sealing in opposite axial directions.

United States Patent [191 Kurio et a].

[I 3,796,436 [451 Mar. 12, 1974 i OIL SEAL DEVICE FOR ROTARY PISTONINTERNAL COMBUSTION ENGINE [75] Inventors: Noriyuki Kurio, Hiroshima;Hiroshi Minegishi, Kawaguchi, both of Japan [73] Assignees: Toyo KogyoCo., Ltd., Hiroshima;

Nippon Piston Ring, Co.,.Ltd., Tokyo, both of, Japan [22] Filed: Oct. 6,1972 [2]] App]. No.: 295,782

[30] Foreign Application Priority Data Oct. 8, 1971 Japan 46-78636 [52]US. Cl. 277/81 P, 277/86, 418/142 [51] Int. Cl F16j 15/34 [58] Field ofSearch 277/81 R, 811, 81 S, 86, 277/87; 418/142 [5 6] References CitedUNITED STATES PATENTS 2,419,588 4/1947 Pasco 277/86 2,963,306 12/1960Tracy... 277/86 3,129,949 4/1964 Laux 277/86 3,535,061 10/1970 Yamamoto418/142 3,575,541 4/l97l Hamada 277/81 P Primary ExaminerLouis R. PrinceAssistant Examiner-R0bert I. Smith Attorney, Agent, or Firm-Sughrue,Rothwell, Mion, Zinn and Macpeak [57] ABSTRACT In a rotary pistoninternal combustion engine comprising a center housing having atrochoidal inner peripheral surface, side housings provided at bothsides of i said center housing, a three apexed rotary piston is providedthrough an eccentric shaft within a casing formed by said center andside housings. An oil seal device is disposed in an annular grooveformed on a thrust surface of the rotary piston including an oil sealring having an annular recess or an annular step on the rear portionthereof. A U-shaped elastic seal ring is disposed in said annular,recess or step and has two lips slidably and sealingly contacting atleast one radially facing surface of said annular recess, said annularstep or said annular groove, and a spring is disposed between said oi]seal ring and said U-shaped elastic seal ring for. pressing said oil.seal ring and said U- shaped elastic sealing in oppositeaxialdirections.

16 Claims, 5 Drawing Figures PATENTEUMAR 12 m4 -FIG.| PRIOR ART' FIG. 2

OIL SEAL DEVICE FOR ROTARY PISTON INTERNAL COMBUSTION ENGINE BACKGROUNDOF THE INVENTION 1. Field of the Invention This invention relates toimprovements of an oil seal device of a rotary'piston internalcombustion engine which is fitted onto the thrust surface of a rotarypiston so as to maintain oil tightness between the thrust surface of therotary piston and a side housing, and more particularly an. improvedauxiliary seal ring for maintaining sealing between the oil seal ringdisposed in the annular groove provided on the thrust surface of amtarypiston and for maintaining an oil tightness between the thrust surfaceof a rotary piston and the inner surface of the side housing and anannular groove.

2. Description of the Prior Art I GenerallyQth'e oil seal device of arotary piston engine includes an oil seal ring disposed in the annulargroove of a thrust surface of a rotary piston for preventing oil fromleakingbetween the thrust surface of a rotary piston and the innersurface of a side housing. A spring presses the oil seal ring ontotheinner surface of a side housing, and an auxiliary seal ringfor sealingbetween the radially facing surface of an annular groove and theradially facingsurface of an oil seal ring for maintaining oil tightnessbetween the oil-seal ring and the annular groove. This auxiliary sealringcomprises a resilient auxiliary seal ring disposed in an annularrecess provided on either the radially facing surface-f an annulargroove or the radially facing surface of an oil seal ring. V 3

The oil seal device of this type has the following disadvantages: Theresilient auxiliary seal ring has a requirement to be pressed sealinglyon two radially facing surfaces for maintaining a sealing between theradially facingsurface of an annular groove and the radially facingsurface of an oil seal ring. This auxiliary seal ring has the effect ofmaintaining oil tightness between the annular, groove of a thrustsurface and the oil seal, but reduces the effect to maintain an oiltightness between the inner surface of the side housing and the thrustsurface of the rotary piston by the oil seal ring as a result of the oilseal' ring beingdepressed by the spring on the 'inner surface of theside housing. That is, it has the disadvantage to lower thefollowability of an oil seal ring to the inner surface of a side housingby the friction beof an auxiliary seal ring or an annular groove.

it has the disadvantages of being twisted and damaged during operationof the rotary piston engine.

The 'oil seal device disclosed in U. S. Pat. No;

3,506,275, assigned to the common assignee, has the followingdisadvantages: The oil seal ring is pressed rotary piston engine.Therefore, the oil seal must also In the oil seal device of this type ofthe rotary piston to the inner surface of the side housing. In orderthat the oil seal ring moves in the direction vertical to the innersurface of the side housing, the auxiliary seal ring must also follow inthe same direction as that,-but since the auxiliary seal ring is pressedonto the radially facing surfaces of the annular groove and the oil sealring, the followability thereof in the direction is very bad. The

auxiliary seal ring moves very complicatedly as above,

move in the same direction. Since the oil seal ring is' auxiliary sealring between the annular groove and the spring is prevented from movingin the same direction as that part of the auxiliary seal ring betweenthe oil seal ring and the spring. Therefore, this auxiliary seal ring istwisted as a result. As a result, it has the disadvantages that theauxiliary seal ring is damaged and oil is leaked.

SUMMARY OF THE INVENTION It is an object of the present invention toeliminate the above disadvantages of the conventional oil seal deviceand to provide novel and improved oil seal device for a rotary pistonengine.

It is another object of the present invention to provide such a novelseal device where the oil seal ring.

may not be obstructed in movement by the auxiliary seal ring and theauxiliary seal ring may not be damaged so as to have an oil sealingeffect for a long time.

' Other objects and advantages of the present invention will be apparentfrom the following detailed description taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF Til-IE DRAWINGS FIG. 1 is a sectional view of theconventional oil seal device of a rotary piston engine.

FIG. 2 is a'sectional view of one embodiment of the oil seal device ofthe present invention.

FIG. 3 is a sectional view of another embodiment of the oil seal deviceof the present invention.

FIG. 4 is a sectional view of another embodiment of the oil seal deviceof the present invention.

FIG. 5 is a sectional view of another embodiment of the oil seal deviceof the present invention.

In the drawings, the same numerals identify the same part of thedevices. I

DESCRIPTION OF TI-IE PREFERRED EMBODIMENTS FIG. 1. shows a prior art oilseal device 5 of a rotary piston internal combustion engine .(not shown)for maintaining oil tightness between the thrust surface 2 of a rotarypiston 1 and the inner face 4 of the side housing 3. The oil seal device5 is disposed in the annular groove 6 provided on the thrust surface 2of the rotary piston 1. The oil seal ring 7 is provided with an annularrecess 9 on the radially inwardly facing surface 8 thereof and hasdisposed therein an auxiliary resilient seal ring 10. A spring 11 isprovided between the rear surface 12 of the oil seal ring 7 and thebottom 13 of the annular groove 6, and its spring 11 presses the oilseal ring 7 onto the inner surface 4 of the side. housing 3. In the oilseal device 5, the auxiliary seal ring is strongly pressed onto theradially outwardly facing surface 14 for maintaining a sealing betweenthe inwardly facing surface 8 of the oil seal ring 7 and the radiallyoutwardly facing surface 14 of the annular groove 6 as seen in the abovedescription. Therefore, the followability of the oil seal ring 7, underthe spring 12, to the inner face 4 of the side housing 3 is prevented bythe friction between the auxiliary seal ring 10 and the radiallyoutwardly facing surface 14. The outside portion of the auxiliary sealring 7 tends to follow the inner surface 4 of the-side housing 3together with the oil seal ring 7 by the radially outside portion, andits radially inside portion does not follow in the same direction due tothe friction of the annular groove 6. Therefore, the auxiliary seal ringis twisted and damaged during operation of the engine.

FIGS. 2 and 3 show embodiments of the oil seal device of the presentinvention as at 5a and 5b. The oil seal ring 7 is provided with anannular recess 15 on the rear surface 12 thereof. U-shaped auxiliaryseal ring 16a is disposed in the annular recess 15 to maintain sealingbetween the oil seal ring 7 and the annular groove 6. U-shaped auxiliaryseal ring l6a has lips 17 and 18 sealbly and slidingly in contact withthe radially inwardly and outwardly facing surfaces 19 and 20 of theannular recess 15. A wavy spring 11a is so disposed in the annularrecess 15 as to press the bottom portion 210 of the U-shaped auxiliaryseal ring 16a onto the bottom 13 of the annular groove 6 together withpressing the oil seal ring 7 onto the inner surface 4 of the sidehousing 3.

Since the oil seal device of the present invention is thus constructed,the followability of the oil seal ring7 to the inner surface 4 of theside housing 3 is very well achieved without obstructing the axialmovement of the oil seal ring 7 by the auxiliary seal ring 16a toprovide a good sealing effect. When the oil seal ring 7 moves in radialdirection, the lips 17 and 18 of the auxiliary seal ring 16a onlyflexresiliently in the same direction, but the auxiliary seal ring 16a isnot twisted. Therefore, the auxiliary seal ring 16a is not damagedduring operation of the engine, but performs a sealing effect for a longtime.

Since the wavy spring 11b in FIG. 3 is not planar, but linear inmanufacture, the bottom portion 21b of the ll-shaped auxiliary seal ring16 is semi-circular so as to ably in contact with the radially inwardlyand outwardly facing surfaces 23 and 14, respectively. Since theauxiliary seal ring 16c of the oil seal device 5c may be enlarged inthickness, in comparison with the auxiliary seal rings 16a and 16b inFIGS. 2 and 3 and the wavy spring may also be enlarged and their sealingeffect is generally enhanced.

The oil seal device 5d 'in FIG. 5 is different from the oil seal device50 in FIG. 4 in the following points: U- shaped auxiliary elastic sealring 16d has a synthetic resin auxiliary elastic member 16f outside of ametal auxiliary elastic member 16e. This metal auxiliary elastic memberl6e has elasticity to press the lips 17a and 17b of the synthetic resinauxiliary elastic member 16f onto the radially inwardly and outwardlyfacing surfaces 24 and 25 of the annular groove 6 and annular step 220,respectively. Therefore, the auxiliary seal ring 16d continues to sealbetween the annular groove 6 and the oil seal ring 7d without damage forlong usage of the engine. The auxiliary seal ring cannot prevent the oilseal ring 7d from pressing onto the inner surface 4 of the side housing,and accordingly, the followability of the oil seal ringf7d to the innersurface 4 is very good.

Incidentally, the metal auxiliary elastic member l6e and synthetic resinauxiliary elastic member 16f may not always be constructed as anintegral auxiliary seal ring. The auxiliary elastic member 16f ofsynthetic resin may not always surround all the periphery of the metalauxiliary elastic member 16a. That is, it seals between the annulargroove 6 and the oil seal ring 7b with t the result that it may only bethe construction for preventing gas from flowing from the combustionchamber (not shown) of the engine through the annular groove ing surfaceof the oil seal ring. When the oil seal ring moves, the auxiliary sealring may not move. Therefore, even if the rotary piston rotateseccentrically peculiar to the rotary piston engine, the auxiliary sealring may not be twisted nor be damaged. The oil seal ring is notprevented from moving by the auxiliary seal ring, but is directlypressed by the spring axially so that the followability of the oil sealring to the inner surface of the side housing is very good.

The material of the auxiliary seal ring of the present invention may beof any type, if it performs the objects and effects of the presentinvention. Synthetic resin rubber or synthetic resin having goodrefractory and wear resistant properties may be used. Metal materialhaving good refractory and wear resistant properties and resiliency maybe used. That is, the auxiliary seal ring 16a may be any of metalmaterial, synthetic resin, or their combination. I

The distance between the lips of the auxiliary seal ring is preferablylonger than the length of the bottom portion of the auxiliary seal ring.Because the radially outside lip is pressed radially to the outside andthe radially inside lip is pressed radially to the inside, and therespective lips are in linear contact with the radially facing surface,they positively prevent oil from leaking without obstructing themovement of the oil seal ring. And, thus, lip contact with the spring isprevented.

What is claimed is:

1. In an oil seal device for rotary piston internal combustion engineComprising a center housing having a trochoidal inner peripheralsurface, side housing provided at both sides of said center housing, amultiapexed rotary piston mounted for movement within the casing formedby said center and side housing, said oil seal device including an oilring disposed in an annular groove formed on a thrust surface of saidrotary piston facing a side housing, the improvement comprising:

a. said oil seal ring having an annular recess within the rear facethereof facing the bottom of said annular groove,

b. a U-shaped elastic seal ring with lips at opposed ends disposed insaid annular recess,

c. the lips of said U-shaped elastic sealing ring sealingly contactingopposed radially facing surfaces defined at least partially by saidrecess,

d. a spring disposed within said U-shaped elastic seal ring andcontacting the bottom face of said recess and said seal ring to presssaid oil seal ring and said U-shaped elastic seal ring in opposite axialdirec tions.

2. The oil seal device as claimed in claim 1, wherein said recesscomprises an annular step provided on a radially outside rear portion ofsaid oil seal ring and said radially facing surfaces comprise a radiallyfacing surface of said recess and a radiallyfacing surface of saidannular groove.

3. The oil seal device as claimed in claim 1, wherein said recesscomprises an annular step provided on a radially inside rear portion ofsaid oil seal ring and said radially facing surfaces comprise a radiallyfacing surface of said recess and aradially facing surface of saidannular groove.

4. The oil seal device as claimed in claim 1, wherein said annularrecess lies intermediate of the radially inside and radially outsidesurfaces of said oil seal ring,

I and wherein said radially facing surfaces comprise surfaces of the oilseal ring formed by said recess.

said U-shaped elastic seal ring is made of a metallic material.

6. The oil seal device as claimed in claim 1, wherein said U-shapedelastic seal ring is made of a material of synthetic resin or syntheticrubber.

7. The oil seal device as claimed in claim 1, wherein the distancebetween both lips of said U-shaped elastic seal ring is larger than thelength of a bottom portio of said U-shaped elastic seal ring.

8. The oil seal device as claimed in claim 1, wherein said U-shapedelastic seal ring is :made of a composite U-shaped metallic member and aU-shaped nonmetallic member.

9. The oil seal device as claimed in claim 1, wherein said U-shapedelastic seal ring is made of metal coated 'with a synthetic rubbermaterial.

10. The oil seal device as claimed in claim 9, wherein said coatingmaterial comprises the outer surface of said U-shaped elastic seal ring.

1 1. The oil seal device as claimed in claim 9, wherein said coatingmaterial covers at least the lips and the bottom portion of saidU-shaped elastic seal ring.

12. The oil seal device as claimed in claim 1, wherein said U-shapedelastic seal ring is made of metal'coated with a synthetic resin.

13. The oil seal device as claimed in claim 12, wherein said coatingmaterial comprises the outer surface of said U-shaped elastic seal ring.

14. The oil seal device as claimed in claim 12, wherein said coatingmaterial covers at least the lips and the bottom .portion of saidU-shaped elastic seal ring.

15. The oil seal device as claimed in claim 1, wherein said spring ismade of a steel wire.

16. The oil seal device as claimed in claim 15, wherein the bottomportion of said U-shaped elastic seal ring is round to conform to thecircular cross sec tion of said steel wire.

1. In an oil seal device for rotary piston internal combustion enginecomprising a center housing having a trochoidal inner peripheralsurface, side housing providEd at both sides of said center housing, amulti-apexed rotary piston mounted for movement within the casing formedby said center and side housing, said oil seal device including an oilring disposed in an annular groove formed on a thrust surface of saidrotary piston facing a side housing, the improvement comprising: a. saidoil seal ring having an annular recess within the rear face thereoffacing the bottom of said annular groove, b. a U-shaped elastic sealring with lips at opposed ends disposed in said annular recess, c. thelips of said U-shaped elastic sealing ring sealingly contacting opposedradially facing surfaces defined at least partially by said recess, d. aspring disposed within said U-shaped elastic seal ring and contactingthe bottom face of said recess and said seal ring to press said oil sealring and said U-shaped elastic seal ring in opposite axial directions.2. The oil seal device as claimed in claim 1, wherein said recesscomprises an annular step provided on a radially outside rear portion ofsaid oil seal ring and said radially facing surfaces comprise a radiallyfacing surface of said recess and a radially facing surface of saidannular groove.
 3. The oil seal device as claimed in claim 1, whereinsaid recess comprises an annular step provided on a radially inside rearportion of said oil seal ring and said radially facing surfaces comprisea radially facing surface of said recess and a radially facing surfaceof said annular groove.
 4. The oil seal device as claimed in claim 1,wherein said annular recess lies intermediate of the radially inside andradially outside surfaces of said oil seal ring, and wherein saidradially facing surfaces comprise surfaces of the oil seal ring formedby said recess.
 5. The oil seal device as claimed in claim 1, whereinsaid U-shaped elastic seal ring is made of a metallic material.
 6. Theoil seal device as claimed in claim 1, wherein said U-shaped elasticseal ring is made of a material of synthetic resin or synthetic rubber.7. The oil seal device as claimed in claim 1, wherein the distancebetween both lips of said U-shaped elastic seal ring is larger than thelength of a bottom portion of said U-shaped elastic seal ring.
 8. Theoil seal device as claimed in claim 1, wherein said U-shaped elasticseal ring is made of a composite U-shaped metallic member and a U-shapednon-metallic member.
 9. The oil seal device as claimed in claim 1,wherein said U-shaped elastic seal ring is made of metal coated with asynthetic rubber material.
 10. The oil seal device as claimed in claim9, wherein said coating material comprises the outer surface of saidU-shaped elastic seal ring.
 11. The oil seal device as claimed in claim9, wherein said coating material covers at least the lips and the bottomportion of said U-shaped elastic seal ring.
 12. The oil seal device asclaimed in claim 1, wherein said U-shaped elastic seal ring is made ofmetal coated with a synthetic resin.
 13. The oil seal device as claimedin claim 12, wherein said coating material comprises the outer surfaceof said U-shaped elastic seal ring.
 14. The oil seal device as claimedin claim 12, wherein said coating material covers at least the lips andthe bottom portion of said U-shaped elastic seal ring.
 15. The oil sealdevice as claimed in claim 1, wherein said spring is made of a steelwire.
 16. The oil seal device as claimed in claim 15, wherein the bottomportion of said U-shaped elastic seal ring is round to conform to thecircular cross section of said steel wire.